A method of realizing Scale Out is proposed in which a load of a computer is distributed by newly adding a computer separately from the computer which is executing a query where processing contents are defined and migrating some of queries to the added computer in a stream data processing system.
For example, Patent Literature 1 discloses that a cost required for migration is calculated on the basis of definition information defined by queries, the query to be migrated is selected according to the calculated migration cost and the query is migrated by a preset migration method. For the migration method, a copying method of copying data stored by a stream data processor that executes a query at a migration destination and a warm-up method of transmitting the same stream data to both a migration source and a migration destination until data according to the execution of queries at the migration source and at the migration destination coincide are disclosed.